Changing internal pressure to achieve variable thermal conductivity in thermal insulation

Paper in proceedings, 2015

Cold climates might have a variable need for thermal insulation. When there are large heat loads a low Uvalue is preferable, and opposite when heat loads are low and it is cold outdoors. One way to adjust the Uvalue is to change the gas pressure within the insulation. This would be especially effective in nano-porous materials where the relation between pressure and thermal conductivity is stronger. Measurements have been conducted on an aerogel blanket and a fumed silica material. The results show an almost linear dependence in thermal conductivity at pressures between 1 kPa and 100 kPA for both materials. In the measurements, the thermal conductivity increase by a factor between 1.5 and 2.6 (highest conductivity divided by lowest conductivity).